On the Golfwrx forum (and probably others), when one is in, say, the private classifieds cars for sale and one goes to search, one of the options, actually the default option is to "search in this forum" option. In e90post though, one has to go to the advanced search options and then reselect whatever subforum they want.

It would be nice to have that option in the search drop down menu when in any particular subforum. Just an idea.